TCA9548A search sketch pauses

I am trying the following TCA9548A setup as described at Wiring & Test | Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout | Adafruit Learning System

When I run the TCAScanner sketch, the serial output stops at the first channel to which I have a device connected. My serial monitor displays something like:

TCAScanner ready!
TCA Port #0
TCA Port #1
TCA Port #2

If A device is connected on Port #2, and does not continue scanning unless I remove the device or pull the reset.

The TCA9548A Is recognized When doing a I2C scan and does return the address 0x70. I have tested 4 different TCA9548A chips as well as 5 different I2C devices, with the same result, as well as added 10k pull up resistors all round.

Does anyone have any idea what the issue could be?

Do you have a link to the TCAScanner? Have searched for it, but cannot find it.

TCScanner is the second bit of code on the linked page: Wiring & Test | Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout | Adafruit Learning System

I have analyzed my problem further. It seems, that as long as the TCA9548A is not connected to any further devices It replies correctly to

Wire.beginTransmission(0x70);
Wire.endTransmission();

with 0, but if a device is connected to any pin,
It returns 0 the first time only, after that it returns 3, though in both cases it does not find the device attached.

I have found the issue, and I feel really stupid. Due to a new breadboard with different power lines The I2C devices were not attached to power.